1. Field of the Invention
The present invention is related to electronic controls for an actuator and more particularly to a method and apparatus for providing feedback for an electronic controller.
2. Description of Relating Art
Actuators of many types are controlled using feedback control. The control logic may be embodied in analog control circuits or digital controllers. Digital control me be accomplished using many different types of devices, such as programmable logic controllers (PLC) or microprocessor based electronic control modules.
One example of an actuator is a brake caliper of a braking system of a motor vehicle. The brake caliper is actuated by a controller. Typically, an operator instructs the controller to apply the brake through operation of a brake pedal. The force applied by the brake caliper is modulated through modulation of the brake pedal.
Actuation of the brakes may be divided into a plurality of phases, for example, initial application of the brakes or application of the brakes to bring the vehicle to a complete stop, modulation of the brakes to slow the vehicle to a desired speed, and release of the brakes. During the first and last of these phases, it is desirable to apply maximum voltage and current to the actuator (in a forward or reverse direction). During the middle phase, brake force is modulated as a function of brake pedal position.
Feedback is typically provided through a feedback sensor which directly measures the feedback parameter. For example, in brake systems the feedback supplied to the control is the actual force applied to the brakes. Typically, a force transducer is used.
However, the additional sensor adds cost and complexity to the system. The present invention is aimed at one or more of the problems identified above.
In one aspect of the present invention, a controller for controlling an actuator in response to an input signal is provided The controller detects a position of the actuator, calculates a force applied to the actuator as a function of the detected position using a predetermined formula, and responsively produces a force feedback signal. The controller receives the input signal and the force feedback signal and responsively delivers to the actuator a control signal.
In another aspect of the present invention, a method for controlling an actuator in response to an input signal is provided. The method includes the steps of detecting position of the actuator and calculating a force as a function of the detected position using a predetermined formula, and responsively producing a force feedback signal. The method further includes the step of receiving the input signal and the force feedback signal and responsively delivering to the actuator a control signal.